which end of house to mount fan?

[Nate Nagel]

Am thinking that I'd like to put a vent fan in my attic this year before it gets too hot, to improve attic ventilation. House was built in late

40's and has unusual roof with no soffits, end of roof is almost even with siding. Only ventilation is two vents at each end of the side walls, just under the peak of the roof. Front door of house faces east, so peak of roof runs north-south.

Question is, which end of the house would be preferred to mount the fan, if any, and should it blow or suck?

nate

[hrhofmann]

Put the "attic exhaust" fan on the south side, it will pull in cooler air from the north side of the house than if the exhaust fan was on the north side pulling air in from the south side as the south side of the house faces the sun and heats up the air which then would rise and get sucked into the attic

[Joe]

[mm]

I was going to say leeward, to be helped and not hindered by the prevailing breeze, but I think your argument is stronger. Unless there is a lot of prevailing breeze.

Nate, you may need more ventilation on the opposite end. You can't squeeze blood from a turnip, whatever that means. OTOH, you can do this part first and then check.

[Heathcliff]

It should be mounted to suck air out of the attic and blow it outside. Make sure the vent on the other end is big enough to accommodate the fan's airflow - the instructions should indicate how many square feet of venting you need. As for which end, if it were me I would probably be guided by aesthetic considerations - mount it wherever you will see/hear it less. I agree with the poster who suggested the air on the north side of the house will be cooler, but I suspect the ultimate difference in the attic temperature would be minor. -- H

[Bob F]

So, prevailing winds are always from the southeast? Everywhere in the world? Or do you know where the OP lives?

[Tony]

Hmm, maybe I need a new finger? My prevailing winds are from the south west.

[Ed Pawlowski]

Blows to outside. Mount it on the end that is easiest to wire.

[Steve Barker]

The fan should take air OUT of the attic, and if it were me, i'd put it in the north end. The prevailing wind is *generally* from the south, so if the fan were in the south gable, it would be working against the wind some of the time. Also, make sure you have an adequate venting to accommodate the fan capacity.

[Steve Barker]

Well, since it's Nate, and he's on cox dot net it's pretty safe to think he's in north america. and yes, the prevailing wind is from the south in NA.

[Nate Nagel]

In fact I am on the east coast, DC area to be precise. So yes, at least a lot of our weather comes up from the south. It would be easier to mount the fan on the north side, completely independent of any other considerations (south side has a chimney)

I'm certain that the ventilation is *not* "adequate" by modern standards, hence my consideration of adding the fan. I would add a ridge vent, but the roof is metal and in good condition.

nate

[Jim Elbrecht]

-snip-

Poppycock. I'm in NA & *my* prevailing wind is from the WSW.

I'm on the west bank of a sloping valley that runs north/south. Folks at the top of the hill or other bank probably have a different prevailing wind.

And 'prevailing' winds can come from different directions different times of year.

Search this pdf for 'prevailing' to see a little about NY's winds-- including mention of how some sites have 2 prevailing wind directions

90 degrees apart.

Jim

[Jim Elbrecht]

-snip-

Ran across this one when I was looking for that one again-

that page- "The prevailing wind is generally from the west in New York State"

Jim